Front part of a vehicle body is provided with left and right front side frames and left and right floor frames, which are some of vital structural elements of the vehicle body. When a so-called head-on collision occurs in which a collision force acts on the front surface of the vehicle, the collision force on the front is transferred from the left and right front side frames to the left and right floor frames and dispersed to the rear of the vehicle body. Techniques for improving the left and right front side frames are disclosed in Japanese Patent Application Laid-Open Publication No. 2006-290311 (JP-A 2006-290311) and Japanese Patent Application Laid-Open Publication No. 2009-234495 (JP-A 2009-234495).
In the vehicle body front disclosed in JP-A 2006-290311, the rear halves of the left and right front side frames curve so as to draw closer to each other as they extend rearward, increasing the strength of the curved rear halves. In the vehicle body front disclosed in JP-A-2009-234495, the sudden twisting of the left and right front side frames relative to the collision force from the front is minimized.
Recently, there has been a demand for a technique for efficiently dispersing a collision force from the front through the entire vehicle body. To accomplish this, the floor frames must be firmly joined to the front side frames.
It follows that there is a need for a technique whereby the floor frames can be firmly joined to the front side frames and a collision force acted on the front surface of the vehicle can be efficiently transferred from the front side frames rearwardly of the vehicle body.